It has been known in the past to use the Miller integrator principle to provide a triangular waveform to apply to the deflection plates of various scanning devices. The Miller integrator integrates a square-wave input to produce a triangular output waveform, usually at low voltage levels. Amplifiers were then provided to raise the output triangular waveform to the voltage levels necessary to sweep the scanning plates.
Linearity of the sweeping triangular waveform has long been an important design objective in such circuits. In the past, however, elimination of distortion from the output coupling network was previously achieved by the use of high capacitance, high-voltage output coupling capacitors, which are expensive and bulky, or by the use of special compensating networks that require adjustment for changing load conditions, a complication which is particularly undesirable in ion-implantation systems.
The employment of negative feedback to reduce distortion has, of course, been common practice for many years Its application, however, has been severely limited in systems which include more than two networks having a leading (or lagging) phase characteristic, because of the resulting strong tendency to oscillate. The design compromises required to attain dynamic stability in such systems frequently render their practical execution unfeasible.